Man concealing weapon in coat? (7)
I believe the answer is:
garment
'coat?' is the definition.
(coat is a kind of garment)
'man concealing weapon' is the wordplay.
'man' becomes 'gent' (gent is a kind of man).
'concealing' is an insertion indicator.
'weapon' becomes 'arm' (synonyms).
'gent' enclosing 'arm' is 'GARMENT'.
'in' is the link.
(Other definitions for garment that I've seen before include "Article of dress" , "Piece of clothing" , "stole, perhaps" , "Something put on" , "coat, say" .)